One of the key problems in electronic commerce over the Internet is finding secure and efficient methods of payment for goods and services. Most existing mechanisms support credit card-based payments. The surcharges and delays associated with these transactions, however, present significant problems and make small purchases uneconomic. Mechanisms of micro payment have been developed in order to overcome these problems. Micro payments make it feasible and profitable for merchants to sell information, services and other content over the Internet, even in transaction amounts of a dollar or less.
IBM Corporation (Armonk, N.Y.) has developed a system of Micro Payments, which is described at www.alphaworks.ibm.com. The system enables merchants, such as Internet content providers, to set up “click and pay” links on their Web sites. When an Internet user, referred to herein as a buyer, wishes to receive content from the merchant's site, the user clicks on the appropriate link. A micro payment amount associated by the link, which is set and posted by the merchant, is then automatically transferred from a Client Wallet maintained by the user to the merchant's account. Upon receiving the micro payment, the merchant's Web server downloads the desired content to the buyer, typically in the form of a Web page, which is displayed by the buyer's Web browser. “Content” in this context can comprise substantially any sort of information, entertainment or services that are amenable to this mode of distribution, for example:                Information such as news, financial data, archives, reference sources, sports scores, reviews and consumer information.        Media and entertainment, such as music, video, pictures games and “edutainment.”        On-line services, such as search engines, fax, mail, telephony, billboards and classified advertisements.        Products, particularly software.        
The IBM Micro Payment system includes three main components:                Billing Server, the Micro Payment “bank,” where all server and client management functions are conducted. These functions include adding, disabling and deleting clients; setting credit limits and commission rates; establishing relationships with other Billing Servers; processing payment to merchant accounts; and signing daily certificates.        Merchant Server, maintained by the merchant, enabling the merchant to manage merchant accounts with the Billing Server; and to set up Hypertext Mark-up Language (HTML) Page Per Fee (“click and pay”) links and to collect micro payments from buyers who use the links.        Client Wallet, used by the buyer to open and maintain buyer accounts with the Billing Server and to purchase items sold through Page Per Fee links.The Billing Server sends a daily credential to the buyer. To make a purchase, the buyer proves his identity and creditworthiness by sending a signed purchase order message to the merchant and attaching the credential. (These functions are performed automatically by a plug-in to the buyer's browser.) The merchant then returns the requested Web page or pages to the buyer, after verifying the purchase order with the Billing Server if desired. Periodically, the Merchant Server deposits the purchase orders it has received with the Billing Server and receives in return the designated payment amount, less commissions charged by any Billing Servers that are involved.        
Payment of commissions for sales referrals is a well-known business model, which has been extended to the realm of electronic commerce. For example, it is common for one Web site to post an advertisement for goods or services for sale on another Web site. The HTML code of the advertisement typically contains a uniform resource locator (URL) leading to the seller's site. When a user clicks on such an advertisement, the seller's Web page opens on the user's browser, and the user is invited to make the purchase. The advertiser is compensated on the basis of the number of “click-throughs” to the seller's site and/or as a percentage on sales made on such click-throughs. Methods of on-line advertising are described, for example, in U.S. Pat. Nos. 5,305,195 and 5,937,392, whose disclosures are incorporated herein by reference.
While there are various solutions known in the art that enable the advertiser to count the number of click-throughs to the seller's site, it is much more difficult to track the percentage commissions that may be due. This difficulty is particularly intractable in the case of micro payments, in which a great many commission payments in very small amounts are typically involved. Generally, the advertiser must simply trust the seller to deliver the commissions as agreed. Typically, the seller identifies the advertiser by a parameter included in the purchase request submitted by the buyer, by a cookie added to the request, or by an identification of the site from which the buyer linked to the seller's site. The advertiser can know that the seller received the request only if the request is sent through the advertiser. Since the commission amounts are typically small (especially when micro payments are involved), advertisers often have to wait a very long time to be paid, until a sufficient amount of commission payments has accumulated.